The present invention relates to a heat sink assembly, and particularly to a heat sink assembly which can provide EMI shielding for protected electronic elements while providing effective heat dissipation.
Computer technology today transmits information at higher and higher rates. As transmission speed increases, the heat produced by the internal electronic elements increases correspondingly. This heat must be dissipated efficiently, otherwise the rising temperature in the computer will cause a system malfunction.
Referring to U.S. Pat. No. 4,884,331, a prior art heat sink assembly comprises a heat sink having a conductive base. A plurality of fins are formed on a top surface of the base and an electronic element is located under the base and abutted against a bottom surface thereof, whereby heat produced by the electronic element is dissipated through the fins on the base. However, using this means, the assembly is fairly high profile, which does not accord with the low profile development trend in computers, and minimal EMI protection is provided. Additionally, one means commonly used to fix such a heat sink assembly to the chip is similar to the structure shown in U.S. Pat. No. 5,621,615. This means provides an uneven retaining force, and therefore the electronic element may not make effective contact with the heat sink, and heat dissipation may be adversely affected.
Another heat sink assembly is shown in FIG. 4. This heat sink assembly comprises a rectangular shaped base 11, a first heat sink 13 mounted on the base 11, a second heat sink 15 also mounted on the base 11 some distance away from the first heat sink 13 and a heat pipe 17 running beneath the two heat sinks. The heat sink assembly is mounted with the second heat sink 15 directly above the electronic element which is to be cooled. Channels 12 and 16 are defined in the middle positions of the first and the second heat sinks 13, 15 to install the heat pipe 17. A fan 19 is mounted on the first heat sink 13 to improve the effectiveness of the heat sink. Although this heat sink assembly is low profile, product assembly is fairly involved.
In addition, the increasing frequency of the signals used in computers is causing increasingly severe EMI shielding problems, which need to be taken into account. However, the aforementioned heat sink assemblies do not provide effective EMI shielding for the electronic elements.
Therefore, a heat sink assembly which can provide EMI shielding for the protected electronic elements is needed.